Define evolution. Describe the contribution of Lamarck.
Evolution is referred to as the changes acquired by a species or a certain population of a species gradually over a long period of time. These changes should be heritable.
Contribution of Lanark
According to the Theory of inheritance of acquired characters or Lamarckism, put forward by Lanark, the use and disuse of an organ leads to acquiring change in the features of that organ. These changes are also inherited by the offspring’s.The favorable variations caused due to use and disuse after a considerably long period of time, results in evolution of a new species.
Choose the one term from the following which includes the other three :
broccoli, wild cabbage, cauliflower, cabbage
”The sex of the children is determined by what they inherit from their father and not their mother.” Justify.
Which of the processes, sexual reproduction or asexual reproduction, brings about maximum variations in the offsprings ?
Define the term ‘evolution’. “Evolution cannot be equated with progress”. Justify this statement. [Delhi]
An individual cannot pass on to its progeny the experiences of its lifetime.” Justify the statement with the help of an example and also give reason for the same. [Foreign]
Name five varieties of vegetables which have been produced from ‘wild cabbage’ by the process of artificial selection.
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Give reason for your answer.
Study the following cross and showing self-pollination in Flf fill in the blank and answer the question that follows
Explain the mechanism of sex determination in humans. [All India]
Or
With the help of a flow chart explain in brief how the sex of a newborn is genetically determined in human beings. Which of the two parents, the mother or the father, is responsible for determination of sex of a child? [Foreign]
State one characteristic which shows that the birds are very closely related to dinosaurs.
Mendel said that the characteristics or traits of organisms are carried from one generation to the next by internal factors which occur in pairs. What is the modern name for these factors ?
In human beings, the statistical probability of getting either a male or female child is 50 : 50. Give a suitable explanation.
The forelimbs of a frog, a bird and a man show the same basic design (or basic structure) of bones. What name is given to such organs ?
A man having blood group O marries a woman having blood group B and they have a daughter. What will be the blood group of the daughter ?
Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species ?
Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms ? Give reason for your answer.
(a) Define ‘natural selection’.
(b) “Only variations that confer an advantage to an individual organism will survive in a population”. Do you agree with this statement ? Give reason for your answer.
Can the wing of butterfly and the wing of a bat be considered homologous organs ? Why or why not ?
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better body design’ why or why not ?
What are homologous organs? Can the wing of a butterfly and the wing of a bat be regarded as homologous? Why? [All India]
Gregor Mendel’s first law of genetics states “Of a pair of contrasted characters, only one can be represented in a gamete by its internal ‘factor’.
(a) Give the modern name for this ‘factor’.
(b) State where these factors are found in gametes.
Write the names of at least three inorganic molecules which helped in the origin of life on the earth.
(a) Explain the terms ‘analogous organs’ and ‘homologous organs’ with examples.
(b) In what way are analogous organs evidence for evolution ?
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Why or why not ?
Distinguish between acquired and inherited traits by giving one example of each. Why are traits acquired during the lifetime of an individual not inherited? [Delhi(C)]
The human beings who look so different from each other in terms of colour, size and looks are said to belong to the same species. Why? Justify your answer. [All India(C)]
Give one example each of characters that are inherited and the ones that are acquired in humans. Mention the difference between the inherited and the acquired characters. [Delhi]
Give an example of body characteristics used to determine how close two species are in terms of evolution and explain it. [All India]